What causes osteoporosis?
Risk factors for developing osteoporosis include:
Steroids (especially if taken by mouth) – Steroids (corticosteroids) are used to treat a number of inflammatory conditions including rheumatoid arthritis. They can affect the production of bone by reducing the amount of calcium absorbed from the gut and increasing calcium loss through the kidneys. If you're likely to need steroids, such as prednisolone, for more than 3 months your doctor will probably suggest calcium and vitamin D tablets, and sometimes other medications, to help prevent osteoporosis.
Read more about steroid tablets.
Lack of oestrogen in the body – If you have an early menopause (before the age of 45) or a hysterectomy where one or both ovaries are removed, this increases your risk of developing osteoporosis. This is because they cause your body's oestrogen production to reduce dramatically, so the process of bone loss will speed up. Removal of the ovaries only (ovariectomy or oophorectomy) is quite rare but is also linked with an increased risk of osteoporosis.
Lack of weight-bearing exercise – Exercise encourages bone development, and lack of exercise means you'll be more at risk of losing calcium from the bones and so developing osteoporosis. Muscle and bone health are linked so it's also important to keep up your muscle strength, which will also reduce your risk of falling.
However, women who exercise so much that their periods stop are also at a higher risk because their oestrogen levels will be reduced.
Poor diet – If your diet doesn’t include enough calcium or vitamin D, or if you're very underweight, you'll be at greater risk of osteoporosis.
Heavy smoking – Tobacco is directly toxic to bones. In women it lowers the oestrogen level and may cause early menopause. In men, smoking lowers testosterone activity and this can also weaken the bones.
Heavy drinking – Drinking a lot of alcohol reduces the body’s ability to make bone. It also increases the risk of breaking a bone as a result of a fall.
Family history – Osteoporosis does run in families, probably because there are inherited factors that affect bone development. If a close relative has suffered a fracture linked to osteoporosis then your own risk of a fracture is likely to be greater than normal. We don’t yet know if a particular genetic defect causes osteoporosis, although we do know that people with a very rare genetic disorder called osteogenesis imperfecta are more likely to suffer fractures.
Other factors that may affect your risk include:
- low body weight
- previous fractures
- medical conditions, such as coeliac disease (or sometimes treatments) that affect the absorption of food.